The Giants’ playmaking safety said he only felt down about missing the entire 2013 season for a couple of days before throwing himself into a vigorous rehab program that appears to have Brown ahead of schedule this spring.

Brown already is back on the field and going through drills at close to full speed during the voluntary organized workouts that began this week, despite the severity of the knee injury suffered in the first quarter of a preseason game against the Jets.

Brown said Thursday he wasted no time getting over the shock of hearing a team doctor inform him as he sat on the turf at MetLife Stadium that his ligament was probably torn.

“I just kind of looked at him and said, ‘Don’t tell me that,’ ” Brown said. “It was one of those things where I may have been down for about two days, but you can’t get better being down on yourself. So I flipped it into getting back into rehab mode and getting back for this year.”

So far, so good.

Stevie Brown #27 of the New York Giants is helped off the field after injuring his leg after making an interception against Geno SmithPhoto: Getty Images

Brown, a journeyman who came out of nowhere in 2012 to lead the Giants with eight interceptions, was working with the first-team defense at safety opposite Antrel Rolle during Thursday’s workout.

“Stevie’s had a good winter,” coach Tom Coughlin said after the 90-minute session at the Giants’ facility. “He’s been in here rehabbing the whole time. He’s running very well, so we’re very happy with that. He is what we call limited, but he’s been able to demonstrate that he has prepared himself well.”

Though Brown’s stint with the starters might be due in large part to the uncertainty surrounding Will Hill’s appeal of his NFL drug suspension, Brown likes to think it is entirely merit-based.

“I know what I can do — it’s just continuing to prove it,” Brown said. “That’s all it is. So I can’t say I’m surprised [by the current starter status].”

Brown’s dedication to his rehab also appeared to convince the Giants to bring him back after letting him test the free-agent market for a brief spell this winter.

Stevie Brown making his 2nd interception of the game in the 4th quarter against in Saints

Brown, 26, said he spoke with a handful of other clubs, but his voice made it clear his heart really wasn’t into going elsewhere. After bouncing around, Brown sounds as if he has found a home with the Giants — and is relieved they felt the same way.

“This is where I wanted to be, and from talking to the coaches and people in the front office, they wanted me to be here, as well,” Brown said. “It was just a matter of getting the deal done.

“Once we got the deal done, I didn’t want to hear my agent say the name of anyone else.”